We use words to describe abstractions which try to model reality as we observe it.
In case of "space time warps in the presence of mass" it's important to understand that this is just a model. Another way to explain it that there is no space-time per se, only masses (with special case of photon et al) and masses interact. What we mean by space-time is that if there was a tiny mass in this given point, it would experience given force. Or, again, modeled differently, travel along given path.
But if there is nothing to interact with, there is no "space-time" per se in this point, after all, it is an abstraction to describe interactions.
So, to sum up, masses interact, space-time is an abstraction to conveniently describe how they interact. Gravitational wave is two massive masses rotating and shaking third small mass as a result of distance changes.
In case of "space time warps in the presence of mass" it's important to understand that this is just a model. Another way to explain it that there is no space-time per se, only masses (with special case of photon et al) and masses interact. What we mean by space-time is that if there was a tiny mass in this given point, it would experience given force. Or, again, modeled differently, travel along given path.
But if there is nothing to interact with, there is no "space-time" per se in this point, after all, it is an abstraction to describe interactions.
So, to sum up, masses interact, space-time is an abstraction to conveniently describe how they interact. Gravitational wave is two massive masses rotating and shaking third small mass as a result of distance changes.